Field of the Invention
The present invention relates to a golf club Shaft.
Description of the Related Art
In a so-called carbon shaft, lightweight properties and high strength are obtained. In the shaft, the wall thickness of a tip portion is generally increased to secure strength while the total wall thickness of the shaft is decreased to secure lightweight properties. The lightweight shaft provides high-speed swing.
For the purpose of a further added value, a shaft having a devised shaft rigidity distribution has been proposed.
Japanese Unexamined Patent Application Publication No. 2011-92319 discloses a shaft which has a flexural rigidity distribution having a first maximal value and a second maximal value. The first maximal value is located in a range of 250 to 350 mm from a tip end, and the second maximal value is located in a range of 400 to 600 mm from the tip end. Furthermore, a flexural rigidity distribution is defined in Japanese Unexamined Patent Application Publication No. 2009-291405 (US2009/0305809) and Japanese Unexamined Patent Application Publication No. 2005-152613 (US2005/0090326).